Nothing to see here folks....move along[8D]

 

maybe this topic can get back on track. The hmf seems to be making almost as much power on 250cc bikes as the full systems are, but it seems like alot of people are bumping up to the 300cc. If the 300 kit is in the furture would the larger dia. head pipe of a full systembe more benifical on the 300 than the 250. This might help make an exhaust choice between slip on/full system easier if you know the 300 kit is going to go on.

 

Let's start-off by working from this fact: The KLX300 and 250 headpipes share the same inner diameter, one is just longer than the other.
The guys at the the thumper talk forum will tell you that the stock KLX300 head pipe is too restrictive. I'm sure you can get plenty of info if you pose the same question to them.Bill P. and Brewster are some of the more knowledgeable posters over there.

The engineer who built the HMFslip-on felt that the KLX250 headpipe was 'right-sized', but it is probably a bit too smallto take full advantage of the300cc displacement (my own conclusion).One of the many reasons I opted for a full system was because I think a 300-331cc upgrade is somewhere in my future.

I'm sure there are plenty of others who will weigh-in on the subject, but I feel a larger headpipewould be awisechoice ifyou are thinking about increasing the displacement.

 

I've been riding 2 strokes all of 20+ years. Ihave and do own4strokes,but my personalpref would be the 2 stroke ,I just miss the snap , my stock klx250 is no torque monster,but It has the magic button,andt ithasn't let me down ,and I'm very happy with the bike overall,.on the slower speed ,rocky trails we've been riding on...I'm looking for Lots more throttle response.thou .for the buck... any suggestions...

 

My pumper carb gave the bike A LOT more snap. If throttle response is what you are looking for, a pumper carb is the weapon of chose. Even on a 250(mine), it makes a world of difference.For 300cc and above, it's match made in heaven. Nobrakes has a pumper on his bike, so there's another source for an impression. There are also several guys at the Thumpertalk KLX/KLR forum who have pumpers and swear by them. Also Marty at KLX world's 'your KLX' forum has a TM33-3012.

The prices range from reasonable (TM33-3012) to fairly expensive (FCR-35 or TM-36). There is also the FCR33, but I don't have much knowledge of that one, since most people I ride withhave an FCR35. Most people at thumper talk own either the FCR35 or the TM33 and all of them seem to be happy with what they have.

 

As tremor said, pumper!

But ... for some pretty good improvement, look up "Grapevine mods" and you will find a procedure for drilling out the slide vent hole on the stock carb. Drill to 7/64's and also rejet while you are in there, open up the airbox, and drill the stock pipe with a 1/2" bit or better yet buy your favorite aftermarket pipe and install that. Do the jetting, airbox, and pipe mods all at once. Especially don't open up the airbox without rejetting since the bike is already running very lean stock you'll be making it leaner if you don't rejet which could damage your head / piston from overheating.

Just the above mods will release a few HP and you'll definitely feel it. But drilling the vacuum slide vent hole is what will give you some more snap with the stock CVK carb. But you may as well do the rest while you are in there.

 

DOH! How could I miss the "my stock KLX!"[8D]

Yes, if you are still running in stock form, definitley do the grapevine mod's. They will noticably improve acceleration and throttle response. If you're still looking for more throttle resonse after the grapevine mod's, a pumper carb willmake a night and day difference even after the mod's.

 

Do I use the Kdx 400 Snorkle? when I open up the airbox? anyone have a link for those basic mods to the KLX250 that were doneon this site... they had part #s and photos..tks

 

Tremor Do you have any links or photos of your bike ? I was hoping you found some black plastics ,for the klx....as I could see from Jpeg image